This invention relates generally to sheet binding, and more particularly to apparatus for binding a plurality of sheets together in a stack to form a book-like assembly. Still more particularly, this invention relates to apparatus employing an adhesive binding member to obtain the bound assembly in a typical business office.
It is often desirable to secure a plurality of sheets of a report, book, or the like together in a bound assembly. While numerous arrangements for binding or assembling sheets together are available, each with certain inherent advantages of its own, many of these known arrangements at the same time suffer certain disadvantages such as high cost, low production rate, or the need for relatively complex applicator machinery, or the inability to edit or otherwise effect changes in a bonded assembly once the bonding operation has been completed.
Perhaps the most common method for assembling pages together is stapling. A staple generally comprises a metallic U-shaped member which is generally formed from drawn wire. The staples are driven under pressure through a stack of sheets and then bent or clinched on the bottom side of the stack to form the permanent assembly. Various mechanical arrangements have heretofore been devised for forming staples into the characteristic U-shaped as well as specific arrangements for inserting and removing the wire staples from the stack. Although the stapling process is employed quite extensively, there are certain disadvantages which are encountered when the aforementioned assembling method is utilized.
For example, the total number of pages that may be stapled together is limited; moreover the resulting product may not have the desired permanency or integrity since the staple or staples may become unhinged, or with sustained use of the book or pamphlet, the pages may tear out or otherwise work loose. Furthermore, the wire staples often times have a tendency to buckle or bend during the process of being driven into the stack of sheets; additionally, sometimes the wire staples are improperly bent or clinched on the underside of the stack. When either of these occur, the improperly inserted staple must therefore be removed and the process repeated until a properly driven and clinched staple is obtained. This results in unnecessary mutilation of the sheets in the stack as well as the consumption of unnecessary operator time in the binding operation.
Where the number of pages are too great for stapling, stitching may be resorted to. However, stitching requires relatively complex and expensive machinery which is normally found only in a bookbinding facility, and not in the business typical office. Additionally the editing of a bonded assembly produced by stitching is quite impractical due to the mutilation of the sheets that is likely to occur. In this latter case, metal clip or clamp assemblies may be resorted to. However, these require some type of punching or drilling mechanism to provide holes in the paper for the clip prongs, and if not performed accurately insofar as the hole formation is concerned, may result in mutilation of the sheets.
It has been proposed to use a binding member comprising a substrate material having an adhesive strip contained thereon to obtain a book-like assembly. However, the members heretofore available have suffered many shortcomings, which have limited their utility. For example, essentially all of the binding members heretofore commercially available have had a single thickness of adhesive of either a low tack material or a high tack material applied onto a substrate material. For instance, it has been the practice ot provide a uniformly thick low tack adhesive coating on a substrate material. If the adhesive coating is applied relatively thin, generally an insufficient amount of adhesive material is provided between the edges of the sheets to be bound. Within relatively short periods of time, individual sheets would work loose from the remaining sheets of the assembly.
Alternatively, if a relatively thick low tack adhesive coating is applied to the substrate material, very often the material flows beyond the limits defined by the substrate material, particularly when the substrate material and low tack adhesive are brought into contact with the outer sheets of the stack. Furthermore, it has proven necessary to permit a heating element used to melt the low tack adhesive and apply pressure thereto so as to unite the substrate material to the outer sheets of a stack to cool to ambient temperature prior to disengagement from the binding member. If this were not permitted, an unsatisfactory bond is obtained since the low tack adhesive must be permitted to solidify before a satisfactory bond is provided. Naturally, the cooling of the heating element prior to disengagement limits the production rate of binding assemblies.
If a high tack adhesive coating were applied to the substrate material, insufficient flow of the adhesive between the sheets would occur due to the high viscosity of the high tack adhesive. Thus, individual sheets would readily separate from the assembly.
A further limitation in the utility of the binding members heretofore available has resulted from the apparatus presently on the commercial market. Binding members employed in such machines must be cut to an appropriate size depending upon the thickness of the stack of sheets being bound. The separate cutting operation required for each binding strip, particularly when the thickness of the stack might vary only a relatively small amount from one stack to the next, has limited the production rate of bound assemblies. Additionally, the separate cutting station required has increased either the cost of the binding apparatus or the labor cost involved in obtaining the bound assembly.
A binding member that has been found to be particularly satisfactory in achieving the desired objectives is disclosed in copending application, Ser. No. 196,446, filed Nov. 1, 1971 in the name of Donald W. Watson and assigned to the assignee of this application. In order to obtain widespread utilization of the binding member disclosed in the aforecited copending application, a satisfactory apparatus wherein such binding member may be employed is required.
However, it should be understood, the method and apparatus disclosed hereinafter are not intended to be limited to use with the binding member disclosed in the aforecited copending application, but may be otherwise employed with binding members heretofore available.